Device for connecting measuring instruments and meters to electrical alternating-current installations



Jan. 13, 1931. A EGGER 1,788,567

DEVICE FOR CONNECTING MESURING INSTRUMENTS AND METERS TO ELECTRICAL ALTERNATING CURRENT INSTALLATIONS Filed Nov. 25, 1929 2 Sheets-Sheet l 7 C la Jan. 13, 1931. A. EGGER 1,788,567

DEVICE EOE CONNECTINC- NEASURING INSTRUMENTS AND METERS To ELECTRICAL ALTEENATING CURRENT INSTALLATIONS Filed Nov. 25, 1929 2 Sheets-Sheet 2 ffy# ' Patented Jan. 13, 1931i` `Y UNITED STATES PATENT l OFFICE ALBERT EGGEE, oEAAEAU, SWITZERLAND, AssIGNon To URBAN EUGMANN, or i AAEAU, SWITZERLANDl DEvIcE Eon coNNEoTINo TIEASUEING INSTRUMENTS ANI)y METERS To ELECTRICAL ALTEENATINGGURRENT INSTALLATIONS j Application med November 25, 1929, serial No. 409,724, and rrr Germany December 2o, 1928.iv

This invention relates to a device for connectingmeasuring instruments and meters to electrical alternating-current installations which permits of readily disconnecting the measuring instruments andmeters as Well as control instruments and short-circuiting current transformers associated therewith.

According to the invention this result is obtained in that terminals v'constituted by separate individual parts are arranged on an insulating body member which parts are adapted to be interconnected by connecting vmembers insertable between the said parts so that each connecting member connects two adjacent terminal parts, suchwise, that by inserting orfremoving the said connecting members the measuring instruments and meters are adapted to be connected or disconnected respectively andthe secondary 1'20 coils of the current transformers with whlch i tion;

Fig. 2 a plan view cover removed;

Fig. 3 a cross-section of the circuit terminalson the lineII-IH inFig. 2; Fig. 4 a cross-section of the voltage terf minals on the line IV-IV in Fig. 2, and Fig. 5 a circuit diagram illustrating the application of the connecting device.V

For simplifying purposes, only kone part of a connecting device fora three-phase inof the same with the stallation V, 7 including a neutral wire O is shown on the drawing (see Fig. 5) the three phases of which, in known manner,

comprise lthree current transformers CT' with which, in known manner, three meters M1, M2, M3 as well as vrecording and measuring instruments, not shown, areV associated. Thereby, 1 t 1s assumed thatan installation of low 4tension is Vinvolvedso that the conductors relatedto the voltage can be directly branched off from the main conductors of the system without the intermediary of the usual voltage transformers In the circuit diagram all the conductors related to the current are indicated in thick lines and those related to the voltage in fine lines. Of the terminals shown in the circuit diagram (Fig. 5), in the Figs. 1 and 2 only one current terminal and one voltage terminal eachserving for one phase are shown. The entity of terminals is mounted on a body member 12 of insulating material con stituted by individual elements 12o and 12u Between the elements 120 and 122i and at their outer end faces insulating inserts 2l are arranged which project beyond 'the lateral sides and the uppery side of the body member, whereby the terminals of the in# dividual phases are separated and insulated fromr each other in effective manner. Each element 12o and 12t is provided adjacent its exterior sides with two bores 12b perpendicularly disposed to its end faces. Screw bolts 13 inserted in the bores 12b unite the elements 12o and l2t to a firm base plate andy serve at the same time for mounting the base plate thus formed between two U-shaped supporting members 14 which, by means of screw bolts 15 passed through the lower flanges 14a'` thereof,` are fastened.` to the switch board S, Whilst screws 16 arranged on the upper flanges 146 of the` supporting members 14 serve for the fixation of the cover 8. Upon the element 12o for one current phase five terminal parts C1, C2, C3,

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C4 and C5 are provided. The first two serve for the connection oli' the incoming branch conduits for the current transformers, by means et corresponding binding screws 22, and the latter three for the connection of the outgoingl branch conduits for the meter, the rirmprcmeter etc., by means of binding' screws 23. Besides, each terminal part is provided with binding screws 24 or respectively tor the connection et branch conduits Jfor test instruments. The individual terminal parts, the cross-section of which follows from Fig. 3, are each secured to the body member by means of two screws 17 which are introduced from the bottom side of the element 12e. Between the individual terminal parts in the element 120 screw nuts 18 are mounted, into which are screwed connecting or short-circuiting` screws 19 or 2O respectively Jirom above, the said screws effecting electrical connection of the corresponding terminal parts exclusively by the underside of their heads when they are completely tightened, whilst the shanlis of the said screws clear the terminal parts, the sides of the same being cut out about the shanlis of the sci-ei as shown in dotted lines in Fig. 2. Thus, when a connection is to be interrupted the corresponding' screws 19 or 20 respectively need not be removed, but merely loosened to the extent that the head is moved out of Contact with the terminal parts. ln the normal operation, the con necting lscews 19 are tightened and the short-circuiting screws 2() loosened. The lower ends of the Shanks of all the screws are provided with an enlarged portion which may be formed in such manner that a small hole is drilled in the shank ot the screw and subsequent to the insertion ot the shank in the nut 18 Athe end portion of the screw enlarged by driving` a pin into the hole in the screw. This enlargement prevents a total rei'nova-l oil the screw and a subsequent possible loosening of the same. Fi'lrthermore, the thickened end of the screw provides a iirm engagement of the latter in the nut 18, whereby, under the influence ot vibrations which are a common phenomenon with alternsolving,` current installations the screw is pre 7ented from tur and self-tightening by moving downwards which might cause an undesired or false contact.

The branch conductors of the meter M of a phase are connected to the terminal. parts C3 and C4 and a branch conductor of the meter oli the one of the other two phases connected. to the terminal partl On the element 12 of the body n carrying` one ci' the four voltage termmals four terminal parts T1, T2, T3 and T-t are secured by means of screws 17 introduced from below. The terminal part T1 which serves for the connection ot' an incoming` voltage branch conductor to the binding screw 2G extends over the full length of the plate element 12a', while the terminal parts T2, T3 and T4 which are separated from each other by the insulating ribs 12?l and to which are connected the voltage branch conductors leading to the meters and measuring instruments of the three phases, by means oli binding screws 27, each occupies but one third part of the available length. For the connection of the three terminal parts T2, 'lll and Tet with the terminal part- Tl connecting screws 21 are used to be screwed into nuts 18 'from above which in the same manner as described in conjunction with the current terminals are embedded in the plate element 12t. The heads of the connecting screws 28 are provided with insulating caps 28a.

The circuit diagram Fig. shows besides the normally connected meters M1, M2 and M3 three control wattmeters VVM1, VM2, 7h/[3 which serve 'for testing purposes. Dependingupon the position occupied, thereby, by the connecting screws 19 or the short circ-uiting screws 20 respectively either the meters or the control instrument-s or both can be connected and when all the instruments are disconnected the secondary circuit of the corresponding current transformer can be short-circuited by means ot the shorteircuiting screws between the terminal parte C1 and C2, in simple manner, so that the generation of undue voltages in the secondary circuit can be avoided.

I claim:

1. In a device for connecting measuring instruments and meters to electrical alternatingv current installations, the combination with, an insulating body member, current terminals secured to the said body member, each of the said current terminals consisting;y of five separate electrically insulated parts, oit Contact screws tor the said insulated parts, the said contact screws providing electrical connection between the said. terminal parte, the head of each oi the said screws being; pressed against two adjacent terminal parts when the screw screwed in the said body member be... een the corresponding# terminal parts, and ot bindingr screws provided on cach teri'z'xina part tor t-he connection of test conductors. the whole arrangement permitting to connect meters and test instruments or to s )ort-circuit the secondary coils of the current tr: *tormcrs when all the measuring instruments are disconnected respectiif'ely so ci o avoid undue voltages in the current 2. In a device for ecimed-inn; meataurino` instruments and meters to electrical alternatinnr current installations, the combination with, an insuladaingl body member, voltage terminals secured to the said body member, each o'l the said voltage terminals consisting of four separate electrically insulated parts7 one of the saidV terminal parts for the recep-` tion of an incoming voltage branch conductor being placed `opposite the three other terminal parts forthe connection of thel outgoing voltage branch conductors, of contact screws for the said terminal parts and of insulated caps on the heads of the said contact screws, suchwise, that by screwingfone of the said screws in the body member between each two olf' the oppcsitely disposed terminal parts electrical connection is provided between the said terminal parts by therhead of the respective screw bearing on both-of the said terminal parts. Y y

3. In adevice for connecting measuring instruments and meters to electrical alter,- nating current installations, the combination with, an insulating base plate, the said base plate'being constituted by individual plate elements, each of the said plate elements be-V ing adapted to receive a terminal, each of the said terminals being constituted by separate individual parts and secured to one of t-he said plate elements, tivo through-bolts for holding the said plate elements together, the said through-bolts traversing all the said plate elements, two supporting members, one for each end of the said base plate, a cover for the device, a switch board for mounting the device thereto, means for xing the said cover to the said supporting members, means for fixing the said supporting member to the said switch board, of contact members for the said terminal parts, the said contact members being yinsertable between adjacent terminal parts so as to provide electrical connection with both of the corresponding terminal parts, suchwise, that by inserting or removing the said contact members the measuring instruments and meters adapted to be connected or disconnected respectively and the current transformers with short-circuited.

4. In a device for connecting measuring instruments and meters to electrical alternating current installations, the combination with, an insulating base plate, the said base plate being constituted by individual plate elements, each of the said plate elements being adapted to receive a terminal, each of the said terminals being constituted by separate individual parts and secured to one of the said plate elements, two through-bolts which the'v are associated are adapted to be i `for holding the said plate elements together,

two bores in each of the said plate elements,

the said through-bolts traversing all the said,

plate elements in the said bores thereof, two supporting members, one for each end of the said base plate, a cover fory the device, a

switch board for mounting the device thereto, means for fixing the said cover to the said supporting member, means `for `fixing vthe said supporting member to the said switch board, of contact members for the said terv are minal partys, the said contact members being insertable between adjacent terminal parts so as to provide electrical connection'with both of theV corresponding terminal parts, suchwise, that by inserting or removing the said contact members the measurmg instru- `ments and metersy are adapted to be con* nected or disconnected respectively and the 

